China is ramping up internal security ahead of a once-in-a-decade leadership change and warned it will swiftly stamp down on social unrest, its powerful top police and judicial official says.

Chinese President Hu Jintao, Premier Wen Jiabao and other leaders will resign from their Communist Party posts at a congress this autumn, ushering in a new leadership for the world's most populous nation.

In a meeting with top government and police officials, Zhou Yongkang, the security chief, ordered a wide-ranging crackdown on unrest, the People's Daily said in a front-page report on Wednesday.

"Safeguarding social harmony and stability is a very important pre-condition for the opening of the 18th Party Congress and is the priority task and political responsibility of every level of government," Zhou said.

"We must deepen and expand the struggle against separatism and terrorism, establish strict preemptions, handle the disruptive activities of domestic and external hostile forces... and strengthen stability maintenance."

Zhou alluded to the tens of thousands of protests that erupt in China every year, ordering local governments to resolve disputes in a wide range of areas including land rows, forced evictions, labour relations, social security and environmental protection, the report said.

Zhou is regarded as an ally of Bo Xilai, a charismatic party figure whose downfall earlier this year triggered the nation's biggest political scandal in decades.

Bo's dramatic demise has reportedly led to turmoil in China's ruling elite ahead of the leadership change.

Zhou was speaking Tuesday as head of the party's influential Politics and Law Commission, which oversees China's courts, prosecution and police.

His commission oversees a budget this year of $111.6 billion -- higher than China's declared military budget -- that is used to suppress political opposition, as well as dissidents in Tibet and Xinjiang.

According to studies published by the China Academy of Social Sciences, the numbers of "mass incidents", or protests, in China grew from 8,700 in 1993 to more than 90,000 in 2006.

Such incidents range from rallies involving only a few dozen people to large street demonstrations with thousands of protesters.